/////////////////////////////////////////////////////////////////////// // File: strokewidth.h // Description: Subclass of BBGrid to find uniformity of strokewidth. // Author: Ray Smith // Created: Mon Mar 31 16:17:01 PST 2008 // // (C) Copyright 2008, Google Inc. // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // http://www.apache.org/licenses/LICENSE-2.0 // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. // /////////////////////////////////////////////////////////////////////// #ifndef TESSERACT_TEXTORD_STROKEWIDTH_H__ #define TESSERACT_TEXTORD_STROKEWIDTH_H__ #include "blobbox.h" // BlobNeighourDir. #include "blobgrid.h" // Base class. #include "colpartitiongrid.h" #include "textlineprojection.h" class DENORM; class ScrollView; class TO_BLOCK; namespace tesseract { class ColPartition_LIST; class TabFind; class TextlineProjection; // Misc enums to clarify bool arguments for direction-controlling args. enum LeftOrRight { LR_LEFT, LR_RIGHT }; // Return value from FindInitialPartitions indicates detection of severe // skew or noise. enum PartitionFindResult { PFR_OK, // Everything is OK. PFR_SKEW, // Skew was detected and rotated. PFR_NOISE // Noise was detected and removed. }; /** * The StrokeWidth class holds all the normal and large blobs. * It is used to find good large blobs and move them to the normal blobs * by virtue of having a reasonable strokewidth compatible neighbour. */ class StrokeWidth : public BlobGrid { public: StrokeWidth(int gridsize, const ICOORD& bleft, const ICOORD& tright); virtual ~StrokeWidth(); // Sets the neighbours member of the medium-sized blobs in the block. // Searches on 4 sides of each blob for similar-sized, similar-strokewidth // blobs and sets pointers to the good neighbours. void SetNeighboursOnMediumBlobs(TO_BLOCK* block); // Sets the neighbour/textline writing direction members of the medium // and large blobs with optional repair of broken CJK characters first. // Repair of broken CJK is needed here because broken CJK characters // can fool the textline direction detection algorithm. void FindTextlineDirectionAndFixBrokenCJK(bool cjk_merge, TO_BLOCK* input_block); // To save computation, the process of generating partitions is broken // into the following 4 steps: // TestVerticalTextDirection // CorrectForRotation (used only if a rotation is to be applied) // FindLeaderPartitions // GradeBlobsIntoPartitions. // These functions are all required, in sequence, except for // CorrectForRotation, which is not needed if no rotation is applied. // Types all the blobs as vertical or horizontal text or unknown and // returns true if the majority are vertical. // If the blobs are rotated, it is necessary to call CorrectForRotation // after rotating everything, otherwise the work done here will be enough. // If osd_blobs is not null, a list of blobs from the dominant textline // direction are returned for use in orientation and script detection. // find_vertical_text_ratio should be textord_tabfind_vertical_text_ratio. bool TestVerticalTextDirection(double find_vertical_text_ratio, TO_BLOCK* block, BLOBNBOX_CLIST* osd_blobs); // Corrects the data structures for the given rotation. void CorrectForRotation(const FCOORD& rerotation, ColPartitionGrid* part_grid); // Finds leader partitions and inserts them into the give grid. void FindLeaderPartitions(TO_BLOCK* block, ColPartitionGrid* part_grid); // Finds and marks noise those blobs that look like bits of vertical lines // that would otherwise screw up layout analysis. void RemoveLineResidue(ColPartition_LIST* big_part_list); // Types all the blobs as vertical text or horizontal text or unknown and // puts them into initial ColPartitions in the supplied part_grid. // rerotation determines how to get back to the image coordinates from the // blob coordinates (since they may have been rotated for vertical text). // block is the single block for the whole page or rectangle to be OCRed. // nontext_pix (full-size), is a binary mask used to prevent merges across // photo/text boundaries. It is not kept beyond this function. // denorm provides a mapping back to the image from the current blob // coordinate space. // projection provides a measure of textline density over the image and // provides functions to assist with diacritic detection. It should be a // pointer to a new TextlineProjection, and will be setup here. // part_grid is the output grid of textline partitions. // Large blobs that cause overlap are put in separate partitions and added // to the big_parts list. void GradeBlobsIntoPartitions(const FCOORD& rerotation, TO_BLOCK* block, Pix* nontext_pix, const DENORM* denorm, bool cjk_script, TextlineProjection* projection, BLOBNBOX_LIST* diacritic_blobs, ColPartitionGrid* part_grid, ColPartition_LIST* big_parts); // Handles a click event in a display window. virtual void HandleClick(int x, int y); private: // Computes the noise_density_ by summing the number of elements in a // neighbourhood of each grid cell. void ComputeNoiseDensity(TO_BLOCK* block, TabFind* line_grid); // Detects and marks leader dots/dashes. // Leaders are horizontal chains of small or noise blobs that look // monospace according to ColPartition::MarkAsLeaderIfMonospaced(). // Detected leaders become the only occupants of the block->small_blobs list. // Non-leader small blobs get moved to the blobs list. // Non-leader noise blobs remain singletons in the noise list. // All small and noise blobs in high density regions are marked BTFT_NONTEXT. // block is the single block for the whole page or rectangle to be OCRed. // leader_parts is the output. void FindLeadersAndMarkNoise(TO_BLOCK* block, ColPartition_LIST* leader_parts); /** Inserts the block blobs (normal and large) into this grid. * Blobs remain owned by the block. */ void InsertBlobs(TO_BLOCK* block); // Fix broken CJK characters, using the fake joined blobs mechanism. // Blobs are really merged, ie the master takes all the outlines and the // others are deleted. // Returns true if sufficient blobs are merged that it may be worth running // again, due to a better estimate of character size. bool FixBrokenCJK(TO_BLOCK* block); // Collect blobs that overlap or are within max_dist of the input bbox. // Return them in the list of blobs and expand the bbox to be the union // of all the boxes. not_this is excluded from the search, as are blobs // that cause the merged box to exceed max_size in either dimension. void AccumulateOverlaps(const BLOBNBOX* not_this, bool debug, int max_size, int max_dist, TBOX* bbox, BLOBNBOX_CLIST* blobs); // For each blob in this grid, Finds the textline direction to be horizontal // or vertical according to distance to neighbours and 1st and 2nd order // neighbours. Non-text tends to end up without a definite direction. // Result is setting of the neighbours and vert_possible/horz_possible // flags in the BLOBNBOXes currently in this grid. // This function is called more than once if page orientation is uncertain, // so display_if_debugging is true on the final call to display the results. void FindTextlineFlowDirection(bool display_if_debugging); // Sets the neighbours and good_stroke_neighbours members of the blob by // searching close on all 4 sides. // When finding leader dots/dashes, there is a slightly different rule for // what makes a good neighbour. // If activate_line_trap, then line-like objects are found and isolated. void SetNeighbours(bool leaders, bool activate_line_trap, BLOBNBOX* blob); // Sets the good_stroke_neighbours member of the blob if it has a // GoodNeighbour on the given side. // Also sets the neighbour in the blob, whether or not a good one is found. // Return value is the number of neighbours in the line trap size range. // Leaders get extra special lenient treatment. int FindGoodNeighbour(BlobNeighbourDir dir, bool leaders, BLOBNBOX* blob); // Makes the blob to be only horizontal or vertical where evidence // is clear based on gaps of 2nd order neighbours. void SetNeighbourFlows(BLOBNBOX* blob); // Nullify the neighbours in the wrong directions where the direction // is clear-cut based on a distance margin. Good for isolating vertical // text from neighbouring horizontal text. void SimplifyObviousNeighbours(BLOBNBOX* blob); // Smoothes the vertical/horizontal type of the blob based on the // 2nd-order neighbours. If reset_all is true, then all blobs are // changed. Otherwise, only ambiguous blobs are processed. void SmoothNeighbourTypes(BLOBNBOX* blob, bool desperate); // Checks the left or right side of the given leader partition and sets the // (opposite) leader_on_right or leader_on_left flags for blobs // that are next to the given side of the given leader partition. void MarkLeaderNeighbours(const ColPartition* part, LeftOrRight side); // Partition creation. Accumulates vertical and horizontal text chains, // puts the remaining blobs in as unknowns, and then merges/splits to // minimize overlap and smoothes the types with neighbours and the color // image if provided. rerotation is used to rotate the coordinate space // back to the nontext_map_ image. // If find_problems is true, detects possible noise pollution by the amount // of partition overlap that is created by the diacritics. If excessive, the // noise is separated out into diacritic blobs, and PFR_NOISE is returned. // [TODO(rays): if the partition overlap is caused by heavy skew, deskews // the components, saves the skew_angle and returns PFR_SKEW.] If the return // is not PFR_OK, the job is incomplete, and FindInitialPartitions must be // called again after cleaning up the partly done work. PartitionFindResult FindInitialPartitions(const FCOORD& rerotation, bool find_problems, TO_BLOCK* block, BLOBNBOX_LIST* diacritic_blobs, ColPartitionGrid* part_grid, ColPartition_LIST* big_parts, FCOORD* skew_angle); // Detects noise by a significant increase in partition overlap from // pre_overlap to now, and removes noise from the union of all the overlapping // partitions, placing the blobs in diacritic_blobs. Returns true if any noise // was found and removed. bool DetectAndRemoveNoise(int pre_overlap, const TBOX& grid_box, TO_BLOCK* block, ColPartitionGrid* part_grid, BLOBNBOX_LIST* diacritic_blobs); // Finds vertical chains of text-like blobs and puts them in ColPartitions. void FindVerticalTextChains(ColPartitionGrid* part_grid); // Finds horizontal chains of text-like blobs and puts them in ColPartitions. void FindHorizontalTextChains(ColPartitionGrid* part_grid); // Finds diacritics and saves their base character in the blob. void TestDiacritics(ColPartitionGrid* part_grid, TO_BLOCK* block); // Searches this grid for an appropriately close and sized neighbour of the // given [small] blob. If such a blob is found, the diacritic base is saved // in the blob and true is returned. // The small_grid is a secondary grid that contains the small/noise objects // that are not in this grid, but may be useful for determining a connection // between blob and its potential base character. (See DiacriticXGapFilled.) bool DiacriticBlob(BlobGrid* small_grid, BLOBNBOX* blob); // Returns true if there is no gap between the base char and the diacritic // bigger than a fraction of the height of the base char: // Eg: line end.....' // The quote is a long way from the end of the line, yet it needs to be a // diacritic. To determine that the quote is not part of an image, or // a different text block, we check for other marks in the gap between // the base char and the diacritic. // '<--Diacritic // |---------| // | |<-toobig-gap-> // | Base | // |---------| x<-----Dot occupying gap // The grid is const really. bool DiacriticXGapFilled(BlobGrid* grid, const TBOX& diacritic_box, const TBOX& base_box); // Merges diacritics with the ColPartition of the base character blob. void MergeDiacritics(TO_BLOCK* block, ColPartitionGrid* part_grid); // Any blobs on the large_blobs list of block that are still unowned by a // ColPartition, are probably drop-cap or vertically touching so the blobs // are removed to the big_parts list and treated separately. void RemoveLargeUnusedBlobs(TO_BLOCK* block, ColPartitionGrid* part_grid, ColPartition_LIST* big_parts); // All remaining unused blobs are put in individual ColPartitions. void PartitionRemainingBlobs(ColPartitionGrid* part_grid); // If combine, put all blobs in the cell_list into a single partition, // otherwise put each one into its own partition. void MakePartitionsFromCellList(bool combine, ColPartitionGrid* part_grid, BLOBNBOX_CLIST* cell_list); // Helper function to finish setting up a ColPartition and insert into // part_grid. void CompletePartition(ColPartition* part, ColPartitionGrid* part_grid); // Merge partitions where the merge appears harmless. void EasyMerges(ColPartitionGrid* part_grid); // Compute a search box based on the orientation of the partition. // Returns true if a suitable box can be calculated. // Callback for EasyMerges. bool OrientationSearchBox(ColPartition* part, TBOX* box); // Merge confirmation callback for EasyMerges. bool ConfirmEasyMerge(const ColPartition* p1, const ColPartition* p2); // Returns true if there is no significant noise in between the boxes. bool NoNoiseInBetween(const TBOX& box1, const TBOX& box2) const; // Displays the blobs colored according to the number of good neighbours // and the vertical/horizontal flow. ScrollView* DisplayGoodBlobs(const char* window_name, int x, int y); // Displays blobs colored according to whether or not they are diacritics. ScrollView* DisplayDiacritics(const char* window_name, int x, int y, TO_BLOCK* block); private: // Image map of photo/noise areas on the page. Borrowed pointer (not owned.) Pix* nontext_map_; // Textline projection map. Borrowed pointer. TextlineProjection* projection_; // DENORM used by projection_ to get back to image coords. Borrowed pointer. const DENORM* denorm_; // Bounding box of the grid. TBOX grid_box_; // Rerotation to get back to the original image. FCOORD rerotation_; // Windows for debug display. ScrollView* leaders_win_; ScrollView* initial_widths_win_; ScrollView* widths_win_; ScrollView* chains_win_; ScrollView* diacritics_win_; ScrollView* textlines_win_; ScrollView* smoothed_win_; }; } // namespace tesseract. #endif // TESSERACT_TEXTORD_STROKEWIDTH_H__